Split End Ring Squirrel-Cage Rotor for Axial Stability

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Solution Overview

Problem

Existing squirrel-cage rotors face challenges in achieving a compact and stable design for short-circuit rings, which affects the mechanical and electrical connectivity of rotor bars, leading to potential axial displacement and vibration issues.

Innovation Solution

The design incorporates short-circuit rings formed from a disk package with recesses and formations, where adjacent disks are spaced apart to create gaps for soldered connections that extend radially inward, providing mechanical strength and electrical conductivity, and using punched and embossed disk material for precise gap control and enhanced cohesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If compact short-circuit rings are used to reduce size, then the rotor becomes more compact, but mechanical strength and stability deteriorate leading to potential delamination and vibrations

Engineering Contradiction:
Improveshort-circuit ring volumeVSAvoidmechanical strength
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The short-circuit ring is divided into multiple individual laminations (at least two) that are stacked together. Each lamination has slots for receiving rotor bars, and the stacked structure provides both compactness and mechanical strength through the layered configuration with interlocking features.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The individual laminations are nested within each other in a stacked arrangement, with each lamination containing slots that receive rotor bars. This nested structure allows the short-circuit ring to maintain a compact form while providing sufficient mechanical strength through the multiple layered components working together.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Stability of the object's composition

If rotor bars are firmly connected to prevent axial displacement, then mechanical stability improves, but the complexity of the connection structure increases

Engineering Contradiction:
Improveaxial stabilityVSAvoidconnection structure complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The laminations are pre-formed with protrusions and recesses that create interlocking features before assembly. The rotor bars are inserted into slots that extend through the laminations, and the protrusions extend beyond the end faces to engage with the rotor bars, preventing axial displacement without requiring additional complex fastening mechanisms.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The short-circuit ring uses a composite structure of multiple laminated plates with different geometric features (slots, protrusions, recesses) that work together. The combination of these laminated components creates a unified structure that provides both mechanical stability and electrical conductivity while maintaining relative simplicity.

Inventive Principle:
Principle #40Composite materials

3Strength

If soldered connections extend radially inward to enclose projections, then mechanical cohesion improves, but manufacturing complexity increases

Engineering Contradiction:
ImprovecohesionVSAvoidmanufacturing ease
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The soldered connection is segmented into two distinct regions: a first region that radially encloses the projections to provide mechanical cohesion, and a second region that fills the remaining gap between the laminations. This segmentation allows each soldering operation to be optimized for its specific function while maintaining manufacturing feasibility.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the gap between laminations receive solder with different functions. The first region receives solder specifically for enclosing projections and providing mechanical strength, while the second region receives solder to fill remaining spaces and provide electrical conductivity. This local differentiation of solder application optimizes both cohesion and manufacturability.

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach results in a compact, cost-effective squirrel-cage rotor with improved mechanical strength and electrical contact between rotor bars and short-circuit rings, reducing axial displacement and vibration while allowing for efficient cooling.

Implementation Method 1

a soldered connection is present in the gap over the outer circumference, which extends radially inwards towards the shaft and encloses the projections

Methodology Applied
Scientific EffectSoldering: Soldering

Data Source

PatentEP3487048B1Squirrel cage rotor comprising split end rings and manufacturing method of such a squirrel cage rotor
Publication Date: 2024.02.28 WIELAND WERKE AG
  • EP3487048B1 patent drawingFigure 1~2
  • EP3487048B1 patent drawingFigure 3~4

AI summary

The invention relates to a squirrel-cage rotor with a shaft (2), a rotor lamination stack (3) with rotor bars (4) arranged inside, and short-circuit rings (5), wherein the short-circuit ring (5) consists of a disk stack (7) which is constructed layer by layer from disks (6) with recesses through which the ends of the rotor bars (4) protrude from the rotor lamination stack (3). Adjacent disks (6) in the disk stack (7) are spaced apart from each other by a gap (8). The space between two adjacent disks (6) caused by the gap is formed by the projections (61) arranged in the disks (6). Additionally, a soldered connection (9) is present in the gap (8), at least in the region of the projections (61). Furthermore, the invention relates to a method for manufacturing a squirrel-cage rotor.